General Description. Serial communication input/output. Serial memory clock. Serial memory data and address. Register backup input.

Transcription

1 Features Provides accurate measurement of available charge in NiCd, NiMH, Li-Ion, and lead-acid batteries Supports SBS Smart Battery Data Specification v. Supports the 2-wire SMBus v. interface with PEC or -wire HDQ6 Reports individual cell voltages Monitors and provides control to charge and discharge FETs in Li-Ion protection circuit Provides 5-bit resolution for voltage, temperature, and current measurements Measures charge flow using a V-to-F converter with offset of less than 6µV after calibration Consumes less than 0.5mW operating Drives a 4- or 5-segment LED display for remaining capacity indication 28-pin 50-mil SSOP Pin Connections General Description The bq2060 SBS-Compliant Gas Gauge IC for battery pack or in-system installation maintains an accurate record of available charge in rechargeable batteries. The bq2060 monitors capacity and other critical battery parameters for NiCd, NiMH, Li-Ion, and lead-acid chemistries. The bq2060 uses a V-to-F converter with automatic offset error correction for charge and discharge counting. For voltage, temperature, and current reporting, the bq2060 uses an A-to-D converter. The onboard ADC also monitors individual cell voltages in a Li-Ion battery pack and allows the bq2060 to generate control signals that may be used in conjunction with a pack supervisor to enhance pack safety. The bq2060 supports the smart battery data (SBData) commands and charge-control functions. It communicates data using the system management bus (SMBus) 2-wire protocol or the Benchmarq -wire HDQ6 protocol. The data available include the battery s remaining capacity, temperature, voltage, current, and remaining run-time predictions. The bq2060 bq2060 SBS v.-compliant Gas Gauge IC Pin Names provides LED drivers and a push-button input to depict remaining battery capacity from full to empty in 20% or 25% increments with a4or 5-segment display. The bq2060 works with an external EEPROM. The EEPROM stores the configuration information for the bq2060, such as the battery s chemistry, self-discharge rate, rate compensation factors, measurement calibration, and design voltage and capacity. The bq2060 uses the programmable self-discharge rate and other compensation factors stored in the EEPROM to accurately adjust remaining capacity for use and standby conditions based on time, rate, and temperature. The bq2060 also automatically calibrates or learns the true battery capacity in the course of a discharge cycle from near full to near empty levels. The REG output regulates the operating voltage for the bq2060 from the battery cell stack using an external JFET. HDQ6 ESCL ESDA RBI REG V OUT V CC V SS DISP LED LED 2 LED 3 LED 4 LED Pin 50-mil SSOP SLUS035D SEPTEMBER SMBC SMBD VCELL 4 VCELL 3 VCELL 2 VCELL SR SR 2 SRC TS THON CVON CFC DFC 28PN2060.eps HDQ6 ESCL ESDA RBI REG V OUT V CC V SS DISP LED LED 5 Serial communication input/output Serial memory clock Serial memory data and address Register backup input Regulator output EEPROM supply output Supply voltage Ground Display control input LED display segment outputs DFC CFC Cell voltage divider con- VON trol THON TS SRC SR SR 2 VCELL VCELL 4 SMBD SMBC Discharge FET control Charge FET control Thermistor bias control Thermistor voltage input Current sense input Charge-flow sense resistor inputs Single-cell voltage inputs SMBus data SMBus clock

2 Pin Descriptions HDQ6 ESCL ESDA RBI REG V OUT V CC V SS DISP LED LED 5 Serial communication input/output Open-drain bidirectional communications port Serial memory clock Output to clock the data transfer between the bq2060 and the external nonvolatile configuration memory Serial memory data and address Bidirectional pin used to transfer address and data to and from the bq2060 and the external nonvolatile configuration memory Register backup input Input that provides backup potential to the bq2060 registers during periods of low operating voltage. RBI accepts a storage capacitor or a battery input. Regulator output Output to control an n-jfet for V CC regulation to the bq2060 from the battery potential Supply output Output that supplies power to the external EEPROM configuration memory Supply voltage input Ground Display control input Input that controls the LED drivers LED LED 5 LED display segment outputs Outputs that each may drive an external LED DFC CFC CVON THON TS SRC SR SR 2 VCELL VCELL 4 SMBD SMBC Discharge FET control output Output to control the discharge FET in the Li-Ion pack protection circuitry Charge FET control output Output to control the charge FET in the Li-Ion pack protection circuitry Cell voltage divider control output Output control for external FETs to connect the cells to the external voltage dividers during cell voltage measurements Thermistor bias control output Output control for external FETs to connect the thermistor bias resistor during a temperature measurement Thermistor voltage input Input connection for a thermistor to monitor temperature Current sense voltage input Input to monitor instantaneous current Sense resistor inputs Input connections for a small value sense resistor to monitor the battery charge and discharge current flow Single-cell voltage inputs Inputs that monitor the series element cell voltages SMBus data Open-drain bidirectional pin used to transfer address and data to and from the bq2060 SMBus clock Open drain bidirectional pin used to clock the data transfer to and from the bq2060 2

3 Functional Description General Operation The bq2060 determines battery capacity by monitoring the amount of charge input or removed from a rechargeable battery. In addition to measuring charge and discharge, the bq2060 measures battery voltage, temperature, and current, estimates battery self-discharge, and monitors the battery for low-voltage thresholds. The bq2060 measures charge and discharge activity by monitoring the voltage across a small-value series sense resistor between the battery s negative terminal and the negative terminal of the battery pack. The available battery charge is determined by monitoring this voltage and correcting the measurement for environmental and operating conditions. Figure shows a typical bq2060-based battery pack application. The circuit consists of the LED display, voltage and temperature measurement networks, EEPROM connections, a serial port, and the sense resistor. The EEPROM stores basic battery pack configuration information and measurement calibration values. The EEPROM must be programmed properly for bq2060 operation. Table 0 shows the EEPROM memory map and outlines the programmable functions available in the bq2060. The bq2060 accepts an NTC thermistor (Semitec 03AT) for temperature measurement. The bq2060 uses the thermistor temperature to monitor battery pack temperature, detect a battery full charge condition, and compensate for self-discharge and charge/discharge battery efficiencies. Measurements The bq2060 uses a fully differential, dynamically balanced voltage-to-frequency converter (VFC) for charge measurement and a sigma delta analog-to-digital converter (ADC) for battery voltage, current, and temperature measurement. Voltage, current, and temperature measurements are made every seconds, depending on the bq2060 operating mode. Maximum times occur with compensated EDV, mwh mode, and maximum allowable discharge rate. Any AtRate computations requested or scheduled (every 20 seconds) may add up to 0.5 seconds to the time interval. Charge and Discharge Counting The VFC measures the charge and discharge flow of the battery by monitoring a small-value sense resistor between the SR and SR 2 pins as shown in Figure. The VFC measures bipolar signals up to 250mV. The bq2060 detects charge activity when V SR =V SR2 V SR is positive and discharge activity when V SR = V SR2 V SR is negative. The bq2060 continuously integrates the signal over time using an internal counter. The fundamental rate of the counter is 6.25µVh. Offset Calibration The bq2060 provides an auto-calibration feature to cancel the voltage offset error across SR and SR 2 for maximum charge measurement accuracy. The calibration routine is initiated by issuing a command to ManufacturerAccess(). The bq2060 is capable of automatic offset calibration down to 6.25µV. Offset cancellation resolution is less than µv. Digital Filter The bq2060 does not measure charge or discharge counts below the digital filter threshold. The digital filter threshold is programmed in the EEPROM and should be set sufficiently high to prevent false signal detection with no charge or discharge flowing through the sense resistor. Voltage While monitoring SR and SR 2 for charge and discharge currents, the bq2060 monitors the battery-pack potential and the individual cell voltages through the VCELL VCELL 4 pins. The bq2060 measures the pack voltage and reports the result in Voltage(). The bq2060 can also measure the voltage of up to four series elements in a battery pack. The individual cell voltages are stored in the optional Manufacturer Function area. The VCELL VCELL 4 inputs are divided down from the cells using precision resistors, as shown in Figure. The maximum input for VCELL VCELL 4 is.25v with respect to V SS. The voltage dividers for the inputs must be set so that the voltages at the inputs do not exceed the.25v limit under all operating conditions. Also, the divider ratios on VCELL VCELL 2 must be half of that of VCELL 3 VCELL 4. To reduce current consumption from the battery, the CVON output may used to connect the divider to the cells only during measurement period. CVON is high impedance for 250ms (2.5% duty cycle) when the cells are measured, and driven low otherwise. See Table. Current The SRC input of the bq2060 measures battery charge and discharge current. The SRC ADC input converts the current signal from the series sense resistor and stores the result in Current(). The full-scale input range to SBC is limited to ±250mV as shown in Table 2. 3

4 Figure. Battery Pack Application Diagram LED Display and Series Cell Monitoring 4

5 Table. Example VCELL VCELL 4 Divider and Input Range Voltage Input Voltage Division Ratio Full-Scale Input (V) VCELL VCELL VCELL VCELL Table 2. SRC Input Range Sense Resistor () Full-Scale Input (A) 0.02 ± ± ± ±2.5 Temperature The TS input of the bq2060 in conjunction with an NTC thermistor measures the battery temperature as shown in Figure. The bq2060 reports temperature in Temperature(). THON may be used to connect the bias source to the thermistor when the bq2060 samples the TS input. THON is high impedance for 60ms when the temperature is measured, and driven low otherwise. Gas Gauge Operation General The operational overview in Figure 2 illustrates the gas gauge operation of the bq2060. Table 3 describes the bq2060 registers. The bq2060 accumulates a measure of charge and discharge currents and estimates self-discharge of the battery. The bq2060 compensates the charge current measurement for temperature and state-of-charge of the battery. The bq2060 also adjusts the self-discharge estimation based on temperature. The main counter RemainingCapacity() (RM) represents the available capacity or energy in the battery at any Figure 2. bq2060 Operational Overview 5

6 given time. The bq2060 adjusts RM for charge, self-discharge, and leakage compensation factors. The information in the RM register is accessible through the communications ports and is also represented through the LED display. The FullChargeCapacity() (FCC) register represents the last measured full discharge of the battery. It is used as the battery s full-charge reference for relative capacity indication. The bq2060 updates FCC when the battery undergoes a qualified discharge from nearly full to a low battery level. FCC is accessible through the serial communications ports. The Discharge Count Register (DCR) is a non-accessible register that only tracks discharge of the battery. The bq2060 uses the DCR register to update the FCC register if the battery undergoes a qualified discharge from nearly full to a low battery level. In this way, the bq2060 learns the true discharge capacity of the battery under system use conditions. Main Gas Gauge Registers RemainingCapacity() (RM) RM represents the remaining capacity in the battery. The bq2060 computes RM in either mah or 0mWh depending on the selected mode. On initialization, the bq2060 sets RM to 0. RM counts up during charge to a maximum value of FCC and down during discharge and self-discharge to 0. In addition to charge and self-discharge compensation, the bq2060 calibrates RM at three low-battery-voltage thresholds, EDV2, EDV, and EDV0 and three programmable midrange thresholds VOC25, VOC50, and VOC75. This provides a voltage-based calibration to the RM counter. DesignCapacity() (DC) The DC is the user-specified battery full capacity. It is calculated from Pack Capacity EE 0x3a 0x3b and is represented in mah or 0mWh. It also represents the full-battery reference for the absolute display mode. FullChargeCapacity() (FCC) FCC is the last measured discharge capacity of the battery. It is represented in either mah or 0mWh depending on the selected mode. On initialization, the bq2060 sets FCC to the value stored in Last Measured Discharge EE 0x38 0x39. During subsequent discharges, the bq2060 updates FCC with the last measured discharge capacity of the battery. The last measured discharge of the battery is based on the value in the DCR register after a qualified discharge occurs. Once updated, the bq2060 writes the new FCC value to EEPROM in mah to Last Measured Discharge. FCC represents the full battery reference for the relative display mode and relative state of charge calculations. Discharge Count Register (DCR) The DCR register counts up during discharge, independent of RM. DCR can continue to count even after RM has counted down to 0. Prior to RM = 0, discharge activity, light discharge estimation and self-discharge increment DCR. After RM = 0, only discharge activity increments DCR. The bq2060 initializes DCR to FCC RM when RM is within twice the programmed value in Near Full EE 0x55. The DCR initial value of FCC RM is reduced by FCC/28 if SC = 0 (bit 2 in Control Mode) and is not reduced if SC =. DCR stops counting when the battery voltage reaches the EDV2 threshold on discharge. Capacity Learning (FCC Update) and Qualified Discharge The bq2060 updates FCC with an amount based on the value in DCR if a qualified discharge occurs. The new value for FCC equals the DCR value plus the programmable nearly full and low battery levels, according to the following equation: FCC(new) DCR(final) () DCR(initial) measured discharge to EDV2 (FCCBatteryLow%) where BatteryLow% (value stored in EE 0x54) A qualified discharge occurs if the battery discharges from RM FCC - Near Full * 2 to the EDV2 voltage threshold with the following conditions: No valid charge activity occurs during the discharge period. A valid charge is defined as an input of 0mAh into the battery. No more than 256mAh of self-discharge and/or light discharge estimation occurs during the discharge period. The temperature does not drop below 5 C during the discharge period. The battery voltage reaches the EDV2 threshold during the discharge period and the voltage was less than the EDV2 threshold minus 256mV when the bq2060 detected EDV2. No midrange voltage correction occurs during the discharge period. FCC cannot be reduced by more than 256mAh or increased by more than 52mAh during any single update cycle. The bq2060 saves the new FCC value to the EEPROM within 4s of being updated. 6

7 Table 3. bq2060 Register Functions Command Code SMBus Function SMBus HDQ6 Access Units ManufacturerAccess 0x00 0x00 read/write n/a RemainingCapacityAlarm 0x0 0x0 read/write mah, 0mWh RemainingTimeAlarm 0x02 0x02 read/write minutes BatteryMode 0x03 0x03 read/write n/a AtRate 0x04 0x04 read/write ma, 0mW AtRateTimeToFull 0x05 0x05 read minutes AtRateTimeToEmpty 0x06 0x06 read minutes AtRateOK 0x07 0x07 read Boolean Temperature 0x08 0x08 read 0. K Voltage 0x09 0x09 read mv Current 0x0a 0x0a read ma AverageCurrent 0x0b 0x0b read ma MaxError 0x0c 0x0c read percent RelativeStateOfCharge 0x0d 0x0d read percent AbsoluteStateOfCharge 0x0e 0x0e read percent RemainingCapacity 0x0f 0x0f read mah, 0mWh FullChargeCapacity 0x0 0x0 read mah, 0mWh RunTimeToEmpty 0x 0x read minutes AverageTimeToEmpty 0x2 0x2 read minutes AverageTimeToFull 0x3 0x3 read minutes ChargingCurrent 0x4 0x4 read ma ChargingVoltage 0x5 0x5 read mv Battery Status 0x6 0x6 read n/a CycleCount 0x7 0x7 read cycles DesignCapacity 0x8 0x8 read mah, 0mWh DesignVoltage 0x9 0x9 read mv SpecificationInfo 0xa 0xa read n/a ManufactureDate 0xb 0xb read n/a SerialNumber 0xc 0xc read integer Reserved 0xd 0xf 0xd - 0xf - - ManufacturerName 0x20 0x20 0x25 read string DeviceName 0x2 0x28 0x2b read string DeviceChemistry 0x22 0x30 0x32 read string ManufacturerData 0x23 0x38 0x3b read string Pack Status 0x2f (LSB) 0x2f (LSB) read/write n/a Pack Configuration 0x2f (MSB) 0x2f (MSB) read/write n/a VCELL4 0x3c 0x3c read/write mv VCELL3 0x3d 0x3d read/write mv VCELL2 0x3e 0x3e read/write mv VCELL 0x3f 0x3f read/write mv 7

8 Table 4. State of Charge Based on Low Battery Voltage Threshold State of Charge in RM EDV0 0% EDV 3% EDV2 Battery Low % End-of-Discharge Thresholds and Capacity Correction The bq2060 monitors the battery for three low-voltage thresholds, EDV0, EDV, and EDV2. The EDV thresholds are programmed in EDVF/EDV0 EE 0x72 0x73, EMF/EDV EE 0x74 0x75, and EDV C/C0 Factor/EDV2 EE 0x78 0x79. If the CEDV bit in Pack Configuration is set, automatic EDV compensation is enabled and the bq2060 computes the EDV0, EDV, and EDV2 thresholds based on the values in EE 0x72 0x7d, 0x06, and the battery s current discharge rate, temperature, capacity, and cycle count. The bq2060 disables EDV detection if Current() exceeds the Overload Current threshold programmed in EE 0x46 - EE 0x47. The bq2060 resumes EDV threshold detection after Current() drops below the overload current threshold. Any EDV threshold detected will be reset after 0mAh of charge are applied. The bq2060 uses the thresholds to apply voltage-based corrections to the RM register according to Table 4. The bq2060 adjusts RM as it detects each threshold. If the voltage threshold is reached before the corresponding capacity on discharge, the bq2060 reduces RM to the appropriate amount as shown in Table 4. If RM reaches the capacity level before the voltage threshold is reached on discharge, the bq2060 prevents RM from decreasing until the battery voltage reaches the corresponding threshold. Self-Discharge The bq2060 estimates the self-discharge of the battery to maintain an accurate measure of the battery capacity during periods of inactivity. The algorithm for self-discharge estimation takes a programmed estimate for the expected self-discharge rate at 25 C stored in EEPROM and makes a fixed reduction to RM of an amount equal to RemainingCapacity()/256. The bq2060 makes the fixed reduction at a varying time interval that is adjusted to achieve the desired self-discharge rate. This method maintains a constant granularity of 0.39% for each self-discharge adjustment, which may be performed multiple times per day, instead of once per day with a potentially large reduction. The self-discharge estimation rate for 25 C is doubled for each 0 degrees above 25 C or halved for each 0 degrees below 25 C. The following table shows the relation of the self-discharge estimation at a given temperature to the rate programmed for 25 C (Y% per day): Temperature ( C) Self-Discharge Rate Temp < 0 Y% per day 4 0 Temp <20 Y% per day 2 20 Temp <30 Y% per day 30 Temp <40 2Y% per day 40 Temp <50 4Y% per day 50 Temp <60 8Y% per day 60 Temp <70 6Y% per day 70 Temp 32Y% per day The interval at which RM is reduced is given by the following equation, where n is the appropriate factor of 2 (n = 4, 2,,2,...): (2) Self Discharge Update Time seconds 256 n ( Y % per day) The timer that keeps track of the self-discharge update time is halted whenever charge activity is detected. The timer is reset to zero if the bq2060 reaches the RemainingCapacity()=FullChargeCapacity() condition while charging. Example: If T = 35 C (n = 2) and programmed self-discharge rate Y is 2.5 (2.5% per day at 25 C), the bq2060 reduces RM by RM/256 (0.39%) every (3) seconds 256n( Y% per day) Figure 3. Self-Discharge at 8

9 This means that a 0.39% reduction of RM will be made 2.8 times per day to achieve the desired 5% per day reduction at 35 C. Figure 3 illustrates how the self-discharge estimate algorithm adjusts RemainingCapacity() vs. temperature. Light Discharge or Suspend Current Compensation The bq2060 can be configured in two ways to compensate for small discharge currents that produce a signal below the digital filter. First, the bq2060 can decrement RM and DCR at a rate determined by the value stored in Light Discharge Current EE 0x2b when it detects no discharge activity and the SMBC and SMBD lines are high. Light Discharge Current has a range of 44µAto.2mA. Alternatively, the bq2060 can be configured to disable the digital filter for discharge when the SMBC and SMBD lines are high. In this way, the digital filter will not mask the leakage current signal. The bq2060 is configured in this mode by setting the NDF bit in Control Mode. Midrange Capacity Corrections The bq2060 applies midrange capacity corrections when the VCOR bit is set in Pack Configuration. The bq2060 adjusts RM to the associated percentage at three different voltage levels VOC25, VOC50, and VOC75. The VOC values represent the open circuit battery voltage at which RM corresponds to the associated state of charge for each threshold. Threshold Associated State of Charge VOC25 25% VOC50 50% VOC75 75% For the midrange corrections to occur, the temperature must be in the range of 9 C to3 C inclusive and the Current() and AverageCurrent() must both be between 64mA and 0. The bq2060 makes midrange corrections as shown in Table 5. Charge Control Charging Voltage and Current Broadcasts The bq2060 supports SBS charge control by broadcasting the ChargingCurrent() and ChargingVoltage() to the Smart Charger address. The bq2060 broadcasts the requests every 0s. The bq2060 updates the values used in the charging current and voltage broadcasts based on the battery s state of charge, voltage, and temperature. The fast-charge rate is programmed in Fast-Charging Current EE 0xa - 0xb while the charge voltage is programmed in Charging Voltage EE 0x0a-0x0b. The bq2060 internal charge control is compatible with popular rechargeable chemistries. The primary charge-termination techniques include a change in temperature over a change in time ( T/ t) and current taper, for nickel-based and Li-Ion chemistries, respectively. The bq2060 also provides pre-charge qualification and a number of safety charge suspensions based on current, voltage, temperature, and state of charge. Alarm Broadcasts to Smart Charger and Host If any of the bits 8 5 in BatteryStatus() is set, the bq2060 broadcasts an AlarmWarning() message to the Host address. If any of the bits 2 5 in BatteryStatus() are set, the bq2060 also sends an AlarmWarning() message to the Smart Charger address. The bq2060 repeats the AlarmWarning() message every 0s until the bits are cleared. Pre-Charge Qualification The bq2060 sets ChargingCurrent() to the pre-charge rate as programmed in Pre-Charge Current EE 0xe-0xf under the following conditions: Table 5. Midrange Corrections Voltage() Condition Result VOC75 and RelativeStateOfCharge() 63% RelativeStateOfCharge() 75% < VOC75 and RelativeStateOfCharge() 87% RelativeStateOfCharge() 75% VOC50 and RelativeStateOfCharge() 38% RelativeStateOfCharge() 50% <VOC50 and RelativeStateOfCharge() 62% RelativeStateOfCharge() 50% VOC25 and RelativeStateOfCharge() 3% RelativeStateOfCharge() 25% < VOC25 and RelativeStateOfCharge() 37% RelativeStateOfCharge() 25% 9

10 Voltage: The bq2060 requests the pre-charge charge rate when Voltage() drops below the EDV0 threshold (compensated or fixed EDVs). Once requested, a pre-charge rate remains until Voltage() increases above the EDVF threshold. The bq2060 also broadcasts the pre-charge value immediately after a device reset until Voltage() is above the EDVF threshold. This threshold is programmed in EDVF/EDV0 EE 0x72-0x73. Temperature: The bq2060 requests the pre-charge rate when Temperature() is between 0 C and 5 C. Temperature() must rise above 5 C before the bq2060 requests the fast-charge rate. Charge Suspension The bq2060 may temporarily suspend charge if it detects a charging fault. A charging fault includes the following conditions. Overcurrent: An overcurrent condition exists when the bq2060 measures the charge current to be more than the Overcurrent Margin above the ChargingCurrent(). Overcurrent Margin is programmed in EE 0x49. On detecting an overcurrent condition, the bq2060 sets the ChargingCurrent() to zero and sets the TERMINATE_CHARGE_ALARM bit in Battery Status(). The overcurrent condition and TERMINATE_ CHARGE_ALARM are cleared when the measured current drops below the ChargingCurrent plus the Overcurrent Margin. Overvoltage: An overvoltage condition exists when the bq2060 measures the battery voltage to be more than the Overvoltage Margin above the ChargingVoltage() or a Li-Ion cell voltage has exceeded the overvoltage limit programmed in Cell Under-/Overoltage. Overvoltage Margin is programmed in EE 0x48 and Cell Under/Over Voltage in EE 0x4a (least significant nibble). On detecting an overvoltage condition, the bq2060 sets the ChargingCurrent() to zero and sets the TERMINATE_CHARGE_ALARM bit in BatteryStatus(). The bq2060 clears the TERMINATE_ CHARGE_ALARM bit when it detects that the battery is no longer being charged (DISCHARGING bit set in BatteryStatus()). The bq2060 continues to broadcast zero charging current until the overvoltage condition is cleared. The overvoltage condition is cleared when the measured battery voltage drops below the ChargingVoltage() plus the Overvoltage Margin or when the CVOV bit is reset. Over-Temperature: An over-temperature condition exists when Temperature() is greater than or equal to the Max T value programmed in EE 0x45 (most significant nibble). On detecting an over-temperature condition, the bq2060 sets the ChargingCurrent() to zero and sets the OVER_TEMP_ALARM and TERMINATE_CHARGE_ ALARM bit in BatteryStatus() and the CVOV bit in Pack Status. The over-temperature condition is cleared when Temperature() is equal to or below (Max T 5 C). Overcharge: An overcharge condition exists if the battery is charged more than the Maxmum Overcharge value after RM = FCC. Maximum Overcharge is programmed in EE 0x2e 0x2f. On detecting an overcharge condition, the bq2060 sets the ChargingCurrent() to zero and sets the OVER_CHARGED_ALARM, TERMINATE_CHARGE_ ALARM, and FULLY_CHARGED bits in BatteryStatus(). The bq2060 clears the OVER_ CHARGED_ALARM and TERMINATE_CHARGE_ ALARM when it detects that the battery is no longer being charged. The FULLY_CHARGED bit remains set and the bq2060 continues to broadcast zero charging current until RelativeStateOfCharge() is less than Fully Charged Clear% programmed in EE 0x4c.The counter used to track overcharge capacity is reset with 2mAh of discharge. Under-Temperature: An under-temperature condition exists if Temperature() < 0 C. On detecting an under temperature condition, the bq2060 sets ChargingCurrent() to zero. The bq2060 sets ChargingCurrent() to the appropriate pre-charge rate or fast-charge rate when Temperature() 0 C. Primary Charge Termination The bq2060 terminates charge if it detects a charge-termination condition. A charge-termination condition includes the following. T/ t: For T/ t, the bq2060 detects a change in temperature over many seconds. The T/ t setting is programmable in both the temperature step, DeltaT (.6 C C), and the time step, DeltaT Time (20s-320s). Typical settings for C/minute include 2 C/20s and 3 C/80s. Longer times are required for increased slope resolution. The DeltaT value is programmed in EE 0x45 (least significant nibble) and the Delta T Time in EE 0x4e. In addition to the T/ t timer, a hold-off timer starts when the battery is being charged at more than 255mA and the temperature is above 25 C. Until this timer expires, T/ t detection is suspended. If Current() drops below 256mA or Temperature() below 25 C, the hold-off timer resets and restarts only when the current and temperature conditions are met again. The hold-off timer is programmable (20s 320s) with Holdoff Time value in EE 0x4f. Current Taper: For current taper, ChargingVoltage() must be set to the pack voltage desired during the constant-voltage phase of charging. The bq2060 detects a current taper termination when the pack voltage is greater than the voltage determined by Current Taper Qual Voltage in EE 0x4f and the charging current is below a threshold determined by Current Taper 0

11 Threshold in EE 0x4e, for at least 40s. The bq2060 uses the VFC to measure current for current taper termination. The current polarity must remain positive as measured by the VFC during this time. Once the bq2060 detects a primary charge termination, the bq2060 sets the TERMINATE_CHARGE_ALARM and FULLY_CHARGED bits in BatteryStatus(), and sets the ChargingCurrent() to the maintenance charge rate as programmed in Maintenance Charging Current EE 0xc 0xd. On termination, the bq2060 also sets RM to a programmed percentage of FCC, provided that RelativeStateOfCharge() is below the desired percentage of FCC and the CSYNC bit in Pack Configuration EE 0x3f is set. If the CSYNC bit is not set and RelativeStateOfCharge() is less than the programmed percentage of FCC, the bq2060 clears the FULLY_CHARGED bit in BatteryStatus(). The programmed percentage of FCC, Fast Charge Termination %, is set in EE 0x4b. The bq2060 clears the FULLY_CHARGED bit when RelativeStateOfCharge() is less than the programmed Fully Charged Clear %. The bq2060 broadcasts the fast-charge rate when the FULLY_CHARGED bit is cleared and voltage and temperature permit. The bq2060 clears the TERMI- NATE_CHARGE_ALARM when it no longer detects that the battery is being charged or it no longer detects the termination condition. See Table 6 for a summary of BatteryStatus() alarm and status bit operation. Display Port General The display port drives a 4 or 5 LED bar-graph display. The display is activated by a logic signal on the DISP input. The bq2060 can display RM in either a relative or absolute mode with each LED representing a percentage of the full-battery reference. In relative mode, the bq2060 uses FCC as the full-battery reference; in absolute mode, it uses DC. The DMODE bit in Pack Configuration programs the bq2060 for the absolute or relative display mode. The LED bit in Control Mode programs the 4 or 5 LED option. A 5th LED can be used with the 4 LED display option to show when the battery capacity is to 00%. Activation The display may be activated at any time by a high-to-low transition on the DISP input. This is usually accomplished with a pullup resistor and a pushbutton switch. Detection of the transition activates the display and starts a four-second display timer. The timer expires and turns off the display whether DISP was brought low momentarily or held low indefinitely. Reactivation of the display requires that the DISP input return to a logic-high state and then transition low again. The second high-to-low transition must occur after the display timer expires. The bq2060 requires the DISP input to remain stable for a minimum of 250ms to detect the logic state. If the EDV0 bit is set, the bq2060 disables the LED display. The display is also disabled during a VFC calibration and should be turned off before entering low-power storage mode. Display Modes In relative mode, each LED output represents 20% or 25% of the RelativeStateOfCharge() value. In absolute mode, each LED output represents 20% or 25% of the AbsoluteStateOfCharge() value. Table 7 shows the display operation. In either mode, the bq2060 blinks the LED display if RemainingCapacity() is less than Remaining CapacityAlarm(). The display is disabled if EDV0 =. Secondary Protection for Li-Ion Undervoltage and overvoltage thresholds may be programmed in the byte value Cell Under/Over Voltage EE 0x4a to set a secondary level of protection for Lithium Ion cells. The bq2060 checks individual cell voltages for undervoltage and overvoltage conditions. The bq2060 displays the results in the Pack Status register and controls the state of the FET control outputs CFC and DFC. If any cell voltage is less than the V UV threshold, the bq2060 sets the CVUV bit in Pack Status and pulls the DFC pin to a logic low. If any cell voltage is greater than the V OV threshold, the bq2060 sets the CVOV bit in Pack Status and pulls the CFC pin to a logic low. Low-Power Storage Mode The bq2060 enters low-power mode 5 8s after receiving the Enable Low-Power command. In this mode the bq2060 consumes less than 0µA. A rising edge on SMBC, SMBD, or HDQ6 restores the bq2060 to the full operating mode. The bq2060 does not perform any gas gauge functions during low-power storage mode. Device Reset The bq2060 can be reset with commands over the HDQ6 or SMBus. Upon reset, the bq2060 initializes its internal registers with the information contained in the configuration EEPROM. The following command sequence initiates a full bq2060 reset: Write Write Write 0x4f to 0xff5a 0x7d to 0x0000 0x7d to 0x0080

12 Battery State Table 6. Alarm and Status Bit Summary Conditions CC() State and BatteryStatus Bits Set CC() = Fast or Pre-charge Current and/or Bits Cleared Overcurrent Overvoltage Overtemperature Overcharge C() CC() + Overcurrent Margin V() CV() + Overvoltage Margin VCELL, 2, 3, or 4 > Cell Over Voltage T() Max T Capacity added after RM() = FCC() Maximum Overcharge CC() = 0, TCA = C() < CC() + Overcurrent Margin TCA = DISCHARGING = CC()=0,CVOV= CC()=0,OTA=, TCA =, CVOV = V() < CV() + Overvoltage Margin Li-Ion cell voltage Cell Over Voltage T() Max T -5 C ort() 43 C CC() = 0, FC = RSOC() < Fully Charged Cleared % OCA =, TCA = DISCHARGING = Undertemperature T() < 0 C CC() = 0 0 C Τ() < 5 C, CC() = Pre-Charge Current T() 5 C, CC() = Fast-Charging Current Fast charge termination T/ t or Current Taper CC() = Maintenance Charging Current, FC= TCA = RSOC() < Fully Charged Cleared % DISCHARGING =ortermination condition is no longer valid. Fully discharged V() EDV2 FD = RSOC() > 20% Overdischarged V() EDV0 TDA = V() > EDV0 VCELL, 2, 3 or 4 < Cell Under Voltage TDA =, CVUV = VCELL, 2, 3, or 4 Cell Under Voltage Low capacity RM() < RCA() RCA = RM() RCA() Low run-time ATTE() < RTA() RTA = ATTE() RTA() Note: C() = Current(), CV() = ChargingVoltage(), CC() = ChargingCurrent(), V() = Voltage(), T() = Temperature(), TCA = TERMINATE_CHARGE_ALARM, OTA = OVER_TEMPERATURE_ALARM, OCA = OVER_CHARGED_ALARM, TDA = TERMINATE_DISCHARGE_ALARM, FC = FULLY_CHARGED, FD = FULLY_DISCHARGED, RSOC() = RelativeStateOfCharge(). RM() = RemainingCapacity(), RCA = REMAINING_CAPACITY_ALARM, RTA = REMAINING_TIME_ALARM, ATTE() = AverageTimeToEmpty(), RTA() = RemainingTimeAlarm(), RCA() = RemainingCapacityAlarm(), FCC() = FullChargeCapacity. 2

13 Table 7A. Display Mode Condition 5 LED Display Option Relative or Absolute StateOfCharge() LED LED2 LED3 LED4 LED5 EDV0 = OFF OFF OFF OFF OFF <20% ON OFF OFF OFF OFF 20%, <40% ON ON OFF OFF OFF 40%, <60% ON ON ON OFF OFF 60%, <80% ON ON ON ON OFF 80% ON ON ON ON ON Communication The bq2060 includes two types of communication ports: SMBus and HDQ6. The SMBus interface is a 2-wire bidirectional protocol using the SMBC (clock) and SMBD (data) pins. The HDQ6 interface is a -wire bidirectional protocol using the HDQ6 pin. All three communication lines are isolated from V CC and may be pulled-up higher than V CC. Also, the bq2060 will not pull these lines low if V CC to the part is zero. HDQ6 should be pulled down with a 00KΩ resistor if not used. The communication ports allow a host controller, an SMBus compatible device, or other processor to access the memory registers of the bq2060. In this way a system can efficiently monitor and manage the battery. SMBus The SMBus interface is a command-based protocol. A processor acting as the bus master initiates communication to the bq2060 by generating a START condition. A START condition consists of a high-to-low transition of the SMBD line while the SMBC is high. The processor then sends the bq2060 device address of 0000 (bits 7 ) plus a R/W bit (bit 0) followed by an SMBus command code. The R/W bit and the command code instruct the bq2060 to either store the forthcoming data to a register specified by the SMBus command code or output the data from the specified register. The processor completes the access with a STOP condition. A STOP condition consists of a low-to-high transition of the SMBD line while the SMBC is high. With SMBus, the most significant bit of a data byte is transmitted first. In some instances, the bq2060 acts as the bus master. This occurs when the bq2060 broadcasts charging requirements and alarm conditions to device addresses 0x2 (SBS Smart Charger) and 0x0 (SBS Host Controller.) Table 7B. Display Mode SMBus Protocol The bq2060 supports the following SMBus protocols: Condition 4 LED Display Option Relative or Absolute StateOfCharge() LED LED2 LED3 LED4 EDV0 = OFF OFF OFF OFF <25% ON OFF OFF OFF 25%, <50% ON ON OFF OFF 50%, <75% ON ON ON OFF 75% ON ON ON ON Read Word Write Word Read Block A processor acting as the bus master uses the three protocols to communicate with the bq2060. The bq2060 acting as the bus master uses the Write Word protocol. The SMBD and SMBC pins are open drain and require external pullup resistors. SMBus Packet Error Checking The bq2060 supports Packet Error Checking as a mechanism to confirm proper communication between it and another SMBus device. Packet Error Checking requires that both the transmitter and receiver calculate a Packet Error Code (PEC) for each communication message. The device that supplies the last byte in the communication message appends the PEC to the message. The receiver compares the transmitted PEC to its PEC result to determine if there is a communication error. PEC Protocol The bq2060 can receive or transmit data with or without PEC. Figure 4 shows the communication protocol for the Read Word, Write Word, and Read Block messages without PEC. Figure 5 includes PEC. In the Write Word protocol, the bq2060 receives the PEC after the last byte of data from the host. If the host does not support PEC, the last byte of data is followed by a STOP condition. After receipt of the PEC, the bq2060 compares the value to its calculation. If the PEC is correct, the bq2060 responds with an ACKNOWLEDGE. If it is not correct, the bq2060 responds with a NOT AC- KNOWLEDGE and sets an error code. 3

14 S 7 Battery Address A Command Code A Data byte low A Data byte high A P Write Word S 7 Battery Address Data byte low A Command Code A S Battery Address A 8 A Data byte high A P Read Word Host Processor S 7 Battery Address A Command Code A S Battery Address A Byte Count =N A Data byte A Data byte 2 A Data byte N A Block Read P bq2060 A ACKNOWLEDGE A NOT ACKNOWLEDGE S START P STOP FG2060HCP.eps Figure 4. SMBus Communication Protocol without PEC S 7 Battery Address A Command Code A Data byte low A Data byte high A PEC A P Write Word 8 S S 7 Battery Address A Command Code A S Battery Address A Data byte low A Data byte high A PEC 7 Battery Address Read Word 8 0 A Command Code A S Battery Address A 7 7 A P Host Processor bq2060 A ACKNOWLEDGE A NOT ACKNOWLEDGE S START P STOP Byte Count =N A Data byte A Data byte 2 A Data byte N A PEC A P Block Read FG2060PEC.eps Figure 5. SMBus Communication Protocol with PEC 4

15 In the Read Word and Block Read, the host generates an ACKNOWLEDGE after the last byte of data sent by the bq2060. The bq2060 then sends the PEC and the host acting as a master-receiver generates a NOT AC- KNOWLEDGE and a STOP condition. PEC Calculation The basis of the PEC calculation is an 8-bit Cyclic Redundancy Check (CRC-8) based on the polynomial C(X) =X 8 +X 2 +X +. The PEC calculation includes all bytes in the transmission, including address, command, and data. The PEC calculation does not include AC- KNOWLEDGE, NOT ACKNOWLEDGE, START, STOP, and Repeated START bits. For example, the host requests RemainingCapacity() from the bq2060. This includes the host following the Read Word protocol. The bq2060 calculates the PEC based on the following 5 bytes of data, assuming the remaining capacity of the battery is 00mAh. Battery Address with R/W = 0: 0x6 Command Code for RemainingCapacity(): 0x0f Battery Address with R/W = : 0x7 RemainingCapacity(): 0x03e9 For 0x60f7e903, the bq2060 transmits a PEC of 0xe8 to the host. PEC Enable in Master Mode PEC for master mode broadcasts to the charger, host, or both can be enabled/disabled with the combination of the bits HPE and CPE in Control Mode. SMBus On and Off State The bq2060 detects whether the SMBus enters the Off State by monitoring the SMBC and SMBD lines. When both signals are continually low for at least 2.5s, the bq2060 detects the Off State. When the SMBC and SMBD lines go high, the bq2060 detects the On State and can begin communication within ms. One-MΩ pulldown resistors on SMBC and SMBD are recommended for reliable Off State detection. HDQ6 The HDQ6 interface is a command-based protocol. (See Figure 6.) A processor sends the command code to the bq2060. The 8-bit command code consists of two fields, the 7-bit HDQ6 command code (bits 0 6) and the -bit R/W field. The R/W field directs the bq2060 either to Store the next 6 bits of data to a specified register or Output 6 bits of data from the specified register With HDQ6, the least significant bit of a data byte (command) or word (data) is transmitted first. A bit transmission consists of three distinct sections. The first section starts the transmission by either the host or the bq2060 taking the HDQ6 pin to a logic-low state for a period t STRH;B. The next section is the actual data-transmission, where the data bit is valid by the time, t DSU;B after the negative edge used to start communication. The data bit is held for a period t DH;DV to allow the host processor or bq2060 to sample the data bit. The final section is used to stop the transmission by returning the HDQ6 pin to a logic-high state by at least the time t SSU;B after the negative edge used to start communication. The final logic-high state should be until a period t CYCH;B to allow time to ensure that the bit transmission was stopped properly. If a communication error occurs (e.g., t CYCB > 250µs), the host sends the bq2060 a BREAK to reinitiate the serial interface. The bq2060 detects a BREAK when the HDQ6 pin is in a logic-low state for a time t B or greater. The HDQ6 pin is then returned to its normal ready-high logic state for a time t BR. The bq2060 is then ready to receive a command from the host processor. The HDQ6 pin is open drain and requires an external pullup resistor. Command Codes The SMBus Command Codes are in ( ), the HDQ6 in [ ]. Temperature(), Voltage(), Current(), and AverageCurrent(), performance specifications are at regulated V CC (V RO ) and a temperature of 0 70 C. ManufacturerAccess() (0x00); [0x00 0x0] Description: This function provides writable command codes to control the bq2060 during normal operation and pack manufacture. These commands can be ignored if sent within one second after a device reset. The following list of commands are available. 0x068 Enable Low-Power Storage Mode: Activates the low-power storage mode. The bq2060 enters the storage mode after a 5 8s delay. The bq2060 accepts other commands to ManufacturerAccess() during the delay before entering low-power storage mode. The LEDs must be off before entering the low-power storage mode as the display state remains unchanged. During the delay following the low-power storage command, a VFC Calibration command may be issued. The bq2060 clears the ManufacturerAccess() command within 900ms of acknowledging the Enable Low-Power Storage command. The VFC Calibration command must be sent ms after SMBus acknowledgment of the Enable Low-Power Storage command. In this case, the bq2060 delays entering storage mode until the calibration process completes and the bq2060 stores the new calibration values in EEPROM. 5

16 0x062b SEAL Command: Instructs the bq2060 to restrict access to those functions listed in Table 3. Note: The SEAL Command does not change the state of the SEAL bit in Pack Configuration in EEPROM. The bq2060 completes the seal function and clears ManufacturerAccess() within 900ms of acknowledging the command. 0x064d Charge Synchronization: Instructs the bq2060 to update RM to a percentage of FCC as defined in Fast Charge Termination %. The bq2060 updates RM and clears ManufacturerAccess() within 900ms of acknowledging the command. 0x0653 Enable VFC Calibration: Instructs the unsealed bq2060 to begin VFC calibration. With this command the bq2060 deselects the SR and SR2 inputs and calibrates for IC offset only. It is best to avoid charge or discharge currents through the sense resistor during this calibration process. 0x067e Alternate VFC Calibration: Instructs the unsealed bq2060 to begin VFC calibration. With this command the bq2060 does not deselect the SR and SR 2 inputs and calibrates for IC and PCB offset. During this procedure no charge or discharge currents During VFC calibration, the bq2060 disables the LED display and accepts only the Stop VFC Calibration and the SEAL Command to ManufacturerAccess(). The bq2060 disregards all other commands. SMBus communication should be kept to a minimum during VFC calibration to reduce the noise level and allow a more accurate calibration. Once started, the VFC calibration procedure completes automatically. When complete, the bq2060 saves the calibration values in EEPROM. The calibration normally takes about 8 to 0 minutes. The calibration time is inversely proportional to the bq2060 VFC (and PCB) offset error. The bq2060 caps the calibration time at one hour in the event of calibrating zero offset error. The VFC calibration can be done as the last step in a battery pack test procedure since the calibration can complete automatically after removal from a test setup. The bq2060 clears ManufacturerAccess() within 900ms and starts calibration within 3.2s of acknowledging the command. 0x0660 Stop VFC Calibration: Instructs the bq2060 to abort a VFC calibration procedure. If aborted, the bq2060 disables offset correction. The bq2060 stops calibration within 20ms of acknowledging the command. 0x0606 Program EEPROM: Instructs the unsealed bq2060 to connect the SMBus to the EEPROM I 2 C bus. The bq2060 applies power to the EEPROM within 900ms of acknowledging the command. After issuing the program EEPROM command, the bq2060 monitoring functions are disabled until the I 2 C bus is disconnected. The bq2060 disconnects the I 2 C bus when it detects that the Battery Address 0x6 is sent over the SMBus. The Battery Address 0x6 to disconnect the I 2 C bus should not be sent until 0ms after the last write to the EEPROM. Example: The following sequence of actions is an example of how to use the ManufacturerAccess() commands in an efficient manner to take a battery pack that has completed all testing and calibration except for VFC calibration and to make it ready for shipment in the SEALED state and in low-power storage mode:. Complete testing and calibration with desired final values stored in EEPROM. This process includes setting the SEAL bit in Pack Configuration. Sending a reset command to the bq2060 during test ensures that RAM values correspond to the final EEPROM values Send Host to bq2060 HDQ Command Code Send Host to bq2060 or Receive from bq bit Data trr Break LSB Bit0 R/W MSB Bit7 trsps Start-bit Address-Bit/ Data-Bit Stop-Bit TD2060CE.eps Figure 6. HDQ6 Communication Example 6

17 2. If the initial value of RemainingCapacity() must be non-zero, the desired value may be written to Command 0x26 with the pack unsealed. A reset sent after this step resets RM to zero. 3. Issue the Enable Low-Power Storage Mode command. 4. Within ms after sending the Enable Low-Power command, issue the Enable VFC Calibration command. This delays the low-power storage mode until after VFC calibration completion. 5. Issue the SEAL Command subsequent to the VFC Calibration command. The bq2060 must receive the SEAL Command before VFC calibration completes. The bq2060 resets the OCE bit in Pack Status when calibration begins and sets the bit when calibration successfully completes. After VFC calibration completes automatically, the bq2060 saves the VFC offset cancellation values in EEPROM and enters the low-power storage mode in about 20s. In addition, the bq2060 is sealed, allowing access as defined in Table 3 only. Purpose: The ManufacturerAccess() function provides the system host access to bq2060 functions that are not defined by the SBD. SMBus Protocol: Read or Write Word Input/ Word RemainingCapacityAlarm() (0x0); [0x0] Description: Sets or gets the low-capacity threshold value. Whenever the RemainingCapacity() falls below the low capacity value, the bq2060 sends AlarmWarning() messages to the SMBus Host with the REMAINING_CAPAC- ITY_ALARM bit set. A low-capacity value of 0 disables this alarm. The bq2060 initially sets the low-capacity value to Remaining Capacity Alarm value programmed in EE 0x04-0x05. The low-capacity value remains unchanged until altered by the Remaining- CapacityAlarm() function. The low-capacity value may be expressed in either current (ma) or power (0mWh) depending on the setting of the BatteryMode() s CAPAC- ITY_MODE bit. Purpose: The RemainingCapacityAlarm() function can be used by systems that know how much power they require to save their operating state. It enables those systems to more finely control the point at which they transition into suspend or hibernate state. The low-capacity value can be read to verify the value in use by the bq2060 s low capacity alarm. SMBus Protocol: Read or Write Word Input/ Unsigned integer value below which Low Capacity messages are sent. Battery Modes CAPACITY_MODE bit=0 CAPACITY_MODE bit= Units C/5 P/5 Range 0 65,535mAh 0 65,535 0mWh Granularity Not applicable Accuracy See RemainingCapacity() RemainingTimeAlarm() (0x02); [0x02] Description: Sets or gets the remaining time alarm value. Whenever the AverageTimeToEmpty() falls below the remaining time value, the bq2060 sends AlarmWarning() messages to the SMBus Host with the REMAINING_TIME_ALARM bit set. A remaining time value of 0 effectively disables this alarm. The bq2060 initially sets the remaining time value to the Remaining Time Alarm value programmed in EE 0x02-0x03. The remaining time value remains unchanged until altered by the RemainingTimeAlarm() function. Purpose: The RemainingTimeAlarm() function can be used by systems that want to adjust when the remaining time alarm warning is sent. The remaining time value can be read to verify the value in use by the bq2060 s RemainingTimeAlarm(). SMBus Protocol: Read or Write Word Input/ Unsigned integer the point below which remaining time messages are sent. Units: minutes Range: 0 to 65,535 minutes Granularity: Not applicable Accuracy: see AverageTimeToEmpty() BatteryMode() (0x03); [0x03] Description: This function selects the various battery operational modes and reports the battery s mode and requests. Defined modes include Whether the battery s capacity information is specified in mah or 0mWh (CAPACITY_MODE bit) Whether the ChargingCurrent() and ChargingVoltage() values are broadcast to the Smart Battery Charger 7